I’m not sure since I don’t read dutch, but my climate.xxx device is the actual thermostat itself. and the state tells me which mode it’s running in (at the moment, Cool).
There’s an attribute called current_temperature you probably want to access (assuming your climate device is like mine).
Probably the easiest was would be to setup a template sensor to capture the attribute you want. I know I’ve seen posts on here this week about something similar, but haven’t done it myself I don’t think.